I chose Greek, but not regret that. I happened to adapt to Greeks play style. Actually the main problem here is, nation perks are not clear for the players in the first place. I thought the decreased build/upgrade times/costs are calculated initially, like 2 hour upgrade on other nations is 1:40 in Greeks. But it wasn't as I expected. Also decreased cost isn't a decreased cost, I have to raid for the same cost with other nations, cost perk is just some tax back. I would like the Greek perks calculated initially, that way Greeks will be more precious.
About Companions, I actually like them. They were really helpful in the early game, I used to send 6 of them in battles. Now I'm in late Medieval Age, a week max to fully upgrade everything and go in to Gunpowder Age, I use only 4 Companions. With all upgrades and researches 4 Companions backed with infantry are enough to bring down catapults easily. I usually send infantry to bring down the Ballista Towers. End of the raid usually all of my Companions get back to the town, I mostly only train lost infantry and get back to raid again in a short time.
Sorry for my bad English as I'm not a native English speaker.